AB0357 INCREASED SOLUBLE INTERLEUKIN 2 RECEPTOR IS ASSOCIATED WITH UNDERWEIGHT IN PATIENTS WITH EARLY RHEUMATOID ARTHRITIS
Authors: H. W. Zheng, J. Pan, Y. W. Zou, J. D. MA, J. Lin, Z. M. Ouyang, Q. Zhang, Q. Y. Song, L. W. Su, Y. Su, L. Dai
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> It have been reported that adipose tissue with proinflammatory properties and obese body mass index (BMI) are involved in rheumatoid arthritis (RA) disease severity. However, less attention was focused on underweight BMI in RA, especially in the early stage. <h3>Objectives</h3> This study aims to investigate the association of underweight with RA disease characteristics and its potential mechanism in early RA. <h3>Methods</h3> This cross-sectional study was carried out retrospectively based on our Chinese RA cohort and controls of general population. Clinical data in RA patients as well as BMI in both RA patients and controls were collected. Early RA patients (disease duration ≤ 12 months) and age- and sex- matched controls were included in this study. Serum levels of inflammatory cytokines including soluble interleukin 2 receptor (sIL-2R), TNF-α, IL-6, IL-1β, IL-8, and IL-10 were detected by chemiluminescent immunoassay. <h3>Results</h3> ① Among 1511 RA patients recruited in the cohort, there were 293 (19.4%) patients with early RA, and 221 early RA patients (mean age 49.4±13.1 years with 69.7% female) and 442 age- and sex- matched (1:2 ratio) controls were eligible for analysis. ② Compared with matched controls, early RA patients had a lower BMI (21.9 ± 3.2 kg/m<sup>2</sup><i>vs.</i> 23.3 ± 2.9 kg/m<sup>2</sup>) together with a higher proportion of underweight (16.3% <i>vs.</i> 2.0%, both <i>P</i> &lt; 0.05). Further compared with matched male controls, male patients with early RA also had a higher proportion of underweight (22.4% <i>vs.</i> 0%, <i>P</i> &lt; 0.001). Surprisingly, compared with female patients, male patients with early RA had a lower BMI (21.1 ± 2.9 kg/m<sup>2</sup><i>vs</i>. 22.3 ± 3.3 kg/m<sup>2</sup>) together with a higher proportion of underweight (22.4% <i>vs.</i> 13.6%, both <i>P</i> &lt; 0.05). On the contrary to patients, matched male controls had a higher BMI (25.0 ± 2.6 kg/m<sup>2</sup><i>vs.</i> 22.6 ± 2.7 kg/m<sup>2</sup>) and less proportion of underweight (0% <i>vs.</i> 2.9%, both <i>P</i> &lt; 0.05) than female controls. ③ Compared with those without underweight, early RA patients with underweight were younger, more male, more active smoking and lower rate of positive ACPA (all <i>P</i> &lt; 0.05). ④ Early RA patients with underweight had a higher level of sIL-2R than those without (median 7.83×10<sup>2</sup> U/ml <i>vs.</i> 4.97×10<sup>2</sup> U/ml, <i>P</i> &lt; 0.001). Spearman correlation analysis showed that BMI was negatively correlated with sIL-2R (<i>r</i> = -0.393, <i>P</i> &lt; 0.001). ⑤ Multivariate logistic regression analysis showed that sIL-2R (OR = 1.127, 95% CI 1.058-1.401) was positively associated with underweight in patients with early RA. <h3>Conclusion</h3> Increased serum sIL-2R was associated with underweight in patients with early RA. The underling mechanism of sIL-2R and underweight in RA need further exploration. <h3>Funding</h3> This study was supported by the National Natural Science Foundation of China (82171780, 81971527, and 82101892), Guangzhou Municipal Science and Technology Project (202102010188), Basic and Applied Basic Research Foundation of Guangdong Province (2019A1515011928, 2020A1515110061, and 2022A1515010524). <h3>Disclosure of Interests</h3> None Declared.